USE/CARE OF HANDTOOLS & MEASURING TOOLS - OD1621 - LESSON 2/TASK 2
d. Care of Thread Chasers.
Never attempt to sharpen thread chasers
yourself as this is a highly specialized cutting process.
precision work on hard tool steel of a shape altogether not suited for
simple stroking on an oilstone.
Store chasers carefully when not in use.
Coat with a light film of oil and rack individually so that the cutting
edges do not touch other metal. For long periods of storage, coat chasers
with a rust preventive compound and store in a dry place.
Screw and Tap Extractors
a. Purpose. Screw extractors are used to remove broken screws without
damaging the surrounding material or the threaded hole. Tap extractors are
used to remove broken taps.
b. Types of Extractors.
Some screw extractors (figure 147) are
straight, having flutes from end to end.
These extractors are used with
twist drills, drill guides, and turn nuts. This type is issued in sizes to
remove screws having 1/4 to 1/2 inch outside diameter. This type is also
issued in a set, enclosed in a metal case. Spiral tapered extractors are
also available in sets that include twist drills. Spiral tapered extractors
are sized to remove screws and bolts from 3/16 inch to 2 1/8 inches outside
SCREW AND TAP EXTRACTORS.